I don't have a whole lot of experience with NTLM, but there's an open source NTLM proxy, "cntlm" (http://cntlm.sourceforge.net/) which you might be able to leverage for this purpose. You could try just configuring your test to use this proxy and see if that works. If there isn't a jmeter plugin that handles ntlm already, someone could probably use the source as the foundation for one. Assuming that there's not a suitable java library that could be used instead...
-- Bruce Ide flyingrhenqu...@gmail.com